新疆某地土壤中有效态钴提取法研究

Study on extraction method for available Co in the soil in an area from Xinjiang

采用火焰原子吸收光谱法测定比较了EDTA、柠檬酸、DTPATEA、Ca(NO3)2和NH4OAc 5种浸提剂对新疆某石化企业污水库周边农田土壤中有效态钴的浸提效果,并将超声浸提法引入常规振荡提取中。采用Tessier连续提取法对试验土壤进行形态分析,并分析了各形态钴与单一浸提剂提取钴量的相关性。结果表明,不同浸提剂对土壤有效态钴的提取率明显不同,提取率均随土壤钴含量升高而升高。浸提剂对有效钴的提取率从大到小依次为柠檬酸、EDTA、DTPATEA、NH4OAc、Ca(NO3)2;5种浸提剂的超声法提取钴量均高于常规振荡法,且EDTA提高程度最大。通过紫花苜蓿盆栽试验可知,柠檬酸、EDTA和DTPA-TEA提取有效态钴量与紫花苜蓿根、茎、叶中钴质量比存在较好相关性,且它们的提取率较高,可作为土壤中有效钴的浸提剂。Tessier连续法提取的各形态钴中,5种浸提剂提取钴量与除残渣态外其余4种形态钴及紫花苜蓿根、茎、叶中富集钴量之间均有较好的相关性。

The paper would like to introduce the extraction method for extracting available Co from the soil in an area from Xinjiang. The method is expected to be used for comparing the extraction effects of Co in the soil by using five types of extractant,that is, EDTA, citric acid, DTPA-TEA, Ca（ NO3）2and NH4 OAc,and the flame atomic absorption spectrometry for the research goal. The soil sample we have taken comes from a farmland surrounded by a petrochemical plant in the said area with the sample being tested via a kind of ultrasonic technique imported in the process of extraction. In our experimental tests,we have done Tessier sequential extraction and then analyzed the forms of Co in the said soil. Further analysis has also been done to disclose the correlation among the five forms of the Co and Co extraction rates by using five types of extractant. The results we have gained indicate that the extraction rates of the corresponding extractants turn to be quite different,though there exists a similar trend that the extraction rates of all the corresponding extractants has been found increasing with the increase of the total content of Co in the soil.To be exact,the descending extraction rate order of the five types of extractant can be represented as follows： citric acid EDTA DTPA-TEA NH4 OAc Ca（ NO3）2. As compared with the conventional vibrating extraction method,it is possible to extract a greater amount of available Co content via the ultrasonic extraction. Of all the five different extractants,the efficiency of EDTA extraction by means of ultrasonic extraction is higher than that extracted by conventional vibrating extraction. Besides,we have also found that there exists a better correlation among the amount of the extracted available Co by using citric acid,EDTA,DTPATEA and Co content in the alfalfa samples. Since it is possible to get a higher extraction efficiency by citric acid,EDTA and DTPA-TEA,they can all be used as the available Co extractants. In addition to the residual form,we have also disclosed there exists an obvious correlation among the extraction rate,four forms Co（ EX,CARB,Fe-Mn,OM） and Co content in the alfalfa samples in the soil of the said area.